A wireless power feeding technology using electric field coupling is attracting attention as a technology to feed power to electronic apparatuses such as mobile devices and notebook personal computers.
In an electric field coupling method, a power feeding apparatus and a power receiving apparatus are provided with electrodes, respectively. By using an electric field generated between the electrodes, electricity is wirelessly transmitted from the power feeding apparatus to the power receiving apparatus.
An electric field coupling method has the advantage that it is easier to align electrodes than other methods such as an electromagnetic induction method. However, the distance between the electrodes of the power feeding apparatus and the power receiving apparatus affects the efficiency of power transmission: that is, the greater the distance between the electrodes, the worse the efficiency is. Therefore, it is desirable that the distance between the electrodes be small.
On the other hand, the efficiency of power transmission worsens if a protrusion is provided on the bottom of an electronic apparatus (power receiving apparatus) such as a mobile device or notebook personal computer, since the distance between the electrodes of the power feeding apparatus and power receiving apparatus is greater.